The "Career Criminal Accountability Act of 2026" amends title 18 of the United States Code to establish a new sentencing framework for "three-strikes offenders." This legislation mandates that sentencing judges determine if a defendant qualifies as a three-strikes offender, requiring them to impose enhanced sentences in accordance with the bill's provisions. The primary goal is to impose stricter penalties on individuals with a history of specific criminal convictions. The bill outlines a system for accruing "strikes" based on prior convictions, categorizing offenses into several types with different strike values. For instance, strike-eligible misdemeanors count as one-quarter strike, nonviolent felonies as one-half strike, and firearm-related or violent felonies each count as one full strike. Special provisions reduce strike counts for offenses committed as a juvenile. A defendant is deemed a three-strikes offender if their current conviction is a strike-eligible felony and they have accrued three or more strikes from prior convictions, with specific rules regarding convictions stemming from single or two episodes of criminal action. Upon qualifying as a three-strikes offender, defendants face mandatory consecutive sentences added to their existing penalties. These enhancements range from 10 years imprisonment for nonviolent felonies, 15 years imprisonment for firearm-related felonies, to life imprisonment for violent felonies under specific conditions. The bill also explicitly prohibits applying these sentencing enhancements solely based on an instant misdemeanor conviction, requiring a subsequent felony conviction for the enhancement to take effect.